This invention relates to molds for injection molding battery containers, the walls of which have thin, resilient, integrally molded ribs projecting at acute angles into the cell compartment(s) defined by the walls. The ribs deflect various amounts according to the thickness of the cell elements comprising the battery's electrochemical innards and serve to firmly retain the innards in the container while cushioning them against vibration. While the invention is most particularly useful for molding multicell, lead-acid, automotive battery containers, it is also applicable to single cell and other types of batteries.
Automobile, SLI, lead-acid storage batteries have standardized outside dimensions in different size categories. The manufacturers thereof typically provide batteries with varying energy capacities in each size category. This is done by varying the number of positive and negative plates in each cell element which comprises the battery's electrochemical innards. Varying the number of plates, however, varies the thickness of the cell element to be positioned and firmly retained in the container's cell compartment(s). Lower energy batteries typically contain about nine plates per cell element while higher energy batteries can contain as high as sixteen plates per element. These elements typically vary in thickness from about 2.42 cm for the low energy batteries to about 4.24 cm for the high energy batteries depending on the number of plates and the particular manufacturer's specifications.
In order to reduce container inventory, some manufacturers have molded universal containers which can readily be modified to accommodate different cell element thicknesses. One such approach is disclosed in U.S. Pat. Thune No. 4,041,603, issued Aug. 16, 1977 and assigned to the assignee of the present invention.
It has also been proposed to mold thin (ca. 0.6 mm) resilient ribs at angles to the container walls, which ribs deflect by an amount commensurate with the thickness of the cell element inserted in the cell compartment. One such approach is disclosed in U.S. Pat. Daniel et al No. 3,607,440, issued Sept. 21, 1971 and assigned to ESB Inc. Heretofore, molding such containers has left the base of the rib attached to the bottom of the container thereby necessitating a separate detaching operation. One such detaching operation is disclosed in copending United States patent application Ser. No. 153,334 filed on May 27, 1980 in the name of Richard H. Kline and assigned to the assignee of the present invention.
It is an object of the present invention to provide a commercially practical mold for injection molding a thermoplastic battery container having thin, inclined, resilient, retainer ribs projecting into the container's cell compartment(s), and which are detached or substantially detached from the bottom of the container in the as-molded condition thereby eliminating a subsequent detaching operation. This and other objects and advantages of the present invention will become more readily apparent from the detailed description thereof which follows.